At least the dinosaurs had an excuse
World-renowned Canadian has a fascinating new theory to explain why the great prehistoric beasts died out - and he can't help but wonder whether humanity will share their fate.
Philip Currie shares his findings with Alanna Mitchell
By ALANNA MITCHELL
Saturday, June 2, 2001
They call it the day the dinosaurs died. It happened 65 million years ago when a massive asteroid punched through the atmosphere and hit Earth with the energy of a hundred million hydrogen bombs. Rocks vapourized on impact and animals burned to a crisp as fire engulfed whole continents, filling the skies with soot. Tidal waves swept the planet.
Then the darkness came and, as a result, the cold. Until, months later, the vast amounts of carbon dioxide released into the atmosphere by the explosions formed a greenhouse gas so potent that it reheated the climate to lethal temperatures.
By the time the temperature had returned to normal, a span of several millenniums, Earth had undergone the fifth great extinction spasm in its history. Perhaps half of all life forms had been wiped out, including the dinosaurs that had ruled the world for 150 million years and were the most sophisticated creatures it had ever seen.
At least, that's the accepted wisdom. But a Canadian expert has come up with a new theory that not only paints a different picture of just why the dinosaur era ground to a halt, but also has an ominous implication for today's dominant life form: extinction.
It's a brisk but gloriously sunny spring day, and Philip Currie and I are in the windswept Alberta badlands looking for dinosaur bones. He shivers in a light jacket, with his hands in his jean pockets and his eyes on the ground. Then he stoops, pokes a long forefinger into the dust and uncovers what looks like a bit of rock.
But the internationally renowned paleontologist and head of research at one of the world's biggest dinosaur museums knows instantly that it is not rock. It is a piece of fossil - from a plant eater, to be specific, most likely the duck-billed hadrosaurus, a resident of the region 70 million years ago. Note the roughness that was once the spongy interior of the bones plant eaters developed to support their great bulk, he explains. Meat eaters such as Tyrannosaurus rex had hollow bones bolstered by an extremely dense outer layer.
Moments later, Currie crouches again, folding his long legs beneath him like a cricket. Triumphantly, he pries loose something that looks just like a square bit of mosaic. "Tendon!" he announces, smiling. The creature was indeed a duckbill - it had tendons running down the spine to stiffen its tail.
This is what Alberta is like for a paleontologist. The badlands that run from Currie's base at the Royal Tyrrell Museum in Drumheller, east of Calgary, south to Dinosaur Provincial Park make up the world's most exquisite bone bed. At any one time, literally millions of fossils are exposed. More complete skeletons have emerged from these few square kilometres than anywhere else on Earth. Big fossils are so plentiful that native people used to consider them proof positive that giants once roamed the planet.
Just as the badlands have lots of evidence of how the dinosaurs lived, they are also uniquely placed to furnish clues about the critical moment when they died.
Until now, most researchers have accepted the asteroid theory as presented in such scientific works as T. rex and the Crater of Doom, written by Walter Alvarez, an esteemed geophysicist at the University of California at Berkeley.
Alvarez, the son of Nobel Prize-winning physicist Luis Alvarez, spent more than a decade researching his thesis that an extraterrestrial body was to blame. In 1991, he finally uncovered the impact site in Mexico, buried under what is now the north coast of the Yucatan Peninsula.
"Rocks are the key to Earth history, because solids remember but liquids and gases forget," he writes in his book. "Retrieving these long-lost memories is the business of geologists and paleontologists, of people who have chosen to be the historians of the Earth."
Currie is one such "historian," but he now suspects that Alvarez does not have the part about the dinosaurs quite right. After 25 years in the field, the Ontario-bred, McGill-educated paleontologist has developed a hypothesis of his own.
He believes that the dinosaurs were in serious trouble when the asteroid hit. For millions of years, they had been struggling to cope with the impact changing weather patterns had had on their ecosystems. So many species had died off that the assault from space was the final blow for the few that remained - if, that is, there were any left at all.
Had the calamity come 10 million years earlier, Currie theorizes, the dinosaurs still would have had enough species and a deep enough gene pool to allow some to survive. As a result, evolution might have taken a vastly different course. The Age of Mammals might never have happened, let alone the Age of Man.
If he is right, the dinosaurs' demise amounts to a dire warning for modern humanity. We are taxing the planet's resources so much that we are pushing species and entire ecosystems over the brink. Currie fears that as we take more and more pieces out of the delicate machinery of Earth, we make ourselves more and more vulnerable just as the dinosaurs were. The result: a much greater chance that a catastrophe, whether another asteroid, a disease or something yet unimagined will spark Armageddon.
"You reduce diversity and then something really major happens," he says, "and you've got a problem."
There is a critical difference, though, between what happened to the dinosaurs and what is happening today. Dinosaurs were the victims of fate. Homo sapiens is orchestrating its own downfall. Humans have become a force of nature - and a malignant one. In effect, we have joined earth, air, water and fire to become the fifth element.
Scientists are finding that each of the planet's critical life-support systems is in jeopardy. Water supplies are being poisoned and exhausted. The air is now so polluted with humanity's carbon dioxide that the weather is being altered. As well, humans have cleared so much of the forest cover and tilled so much land that the carbon cycle has ceased to work properly.
Even fire seems to have lost the power the ancients believed it has over life and death. Now, humans determine what lives and what dies. Because of our actions, 24 per cent of mammal species are in danger of extinction. As well, one-quarter of all reptiles are at risk, plus one-fifth of amphibians, nearly one-third of fish and one in every eight birds, according to the World Conservation Union.
These figures are so high that scientists believe that unless the pace slows, species will vanish more rapidly now than when the dinosaurs died out. The terrible irony is that Homo sapiens, the big winner from the dinosaurs' extinction, is responsible.
Actor Harrison Ford has devoted himself to changing all this, through his work as a board member of Washington-based Conservation International. "Human interference with the natural order of our planet," he explained to me last week, "is the biggest factor in why it is now so fragile."
The risks are huge. "We all know we are losing parts of the biotic continuum at each and every step," he says. "We have no idea, really, what finally the effects of those losses will be."
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